gistfile1.java

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

public class ClassGenerator {
    private List<Class<?>> classList = new ArrayList<>(); 

    public static void main(String[] args) {
        new ClassGenerator().go();
    }

    public void go() {
        while(true) {
            try {
                Class.forName("ClassGenerator", true, createNewClassLoader());
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

    private ClassLoader createNewClassLoader() {
        return new ClassLoader() {
            public Class<?> loadClass(String classNameWithPackage) throws ClassNotFoundException {
                if(!classNameWithPackage.contains("ClassGenerator")) {
                    return super.loadClass(classNameWithPackage);
                } 
                String className = classNameWithPackage.replace('.', '/') + ".class";
                byte[] classData = null;
                InputStream inputStream = null;
                try {
                    inputStream = getResourceAsStream(className);
                    byte[] buffer = new byte[1024];
                    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                    int bytesRead = -1;
                    while ((bytesRead = inputStream.read(buffer)) != -1) {
                        outputStream.write(buffer, 0, bytesRead);
                    }
                    classData = outputStream.toByteArray();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
                finally {
                    if (inputStream != null) {
                        try {
                            inputStream.close();
                        } catch (Exception e) {}
                    }
                }

                Class<?> c = defineClass(classNameWithPackage, classData, 0, classData.length);
                resolveClass(c);
                System.out.println("Steve I am loading another copy of Dummy class. Soon Permgen will fill.");
                classList.add(c);
                return c;
            }
        };
    }
}